Ignition switch utilizing a cam means for restrictive movement unless key is first moved to off position



y 22, 1969 I CRYER 3,457,380

IGNITION SWITCH UTILIZING A CAM MEANS FOR RES CTIVE MOVEMENT UNLESS KEY15 FIRST MOVED TO OFF P0 TION 1 Filed June 8, 1967 I 2 56 J 422 5 I2United States Patent t 3,457,380 IGNITION SWITCH UTILIZING A CAM MEANSFOR RESTRICTIVE MOVEMENT UNLESS KEY IS FIRST MOVED TO OFF POSITIONEdward Cryer, Burnley, England, assignor to Joseph Lucas (Industries)Limited, Birmingham, England Filed June 8, 1967, Ser. No. 644,668 Claimspriority, application Great Britain, June 9, 1966, 25,728/66 Int. Cl.Hlllh 39/00 11.8. Cl. 200-26 1 Claim ABSTRACT OF THE DISCLOSURE Anignition switch for a road vehicle having a part rotatable with therotor of the switch and cooperating with a cam track on the casing ofthe switch to prevent movement of the switch from a position in whichthe ignition circuit of the vehicle is completed to a position in whichthe starter motor circuit is completed unless the switch has previouslybeen moved to a position in which both of said circuits are broken.

This invention relates to ignition switches for use in road vehicles.

An ignition switch for use in a road vehicle having ignition and startercircuits, comprising a casing, a rotor mounted for rotary movementwithin the casing, a first cam track formed within the casing havingdepressions corresponding to auxiliary, off and ignition positions, aradially directed ramp adjacent the ignition position corresponding tothe start position and a stop adjacent the auxiliary position, a secondcam track formed within the casing, said second cam track having a flatarcuate part constituting a ramp, the height of which increases fromzero at a position diametrically opposite the depression correspondingto the off position to a maximum at a position diametrically oppositethe end of the first mentioned cam track, the width of the ramp beingconstant up to a point diametrically opposite the depressioncorresponding to the ignition position, with the ramp having a radiallydirected shoulder at said point and the width of the ramp decreasingfrom a maximum at the shoulder to zero at the highest end of the ramp,spring means for the rotor, said rotor spring means having oppositeends, with one engaged with the rotor and the opposite end extendingtoward the inner wall of the casing, said rotor being provided with aspring-loaded member normally urged into engagement with said first camtrack, said rotor having latch means located substantially diametricallyopposite said spring loaded member, and further spring means operablyrelated to said latch means normally urging said latch means towards thecasing, the arrangement being such that when the switch is in either theoff or auxiliary position, the latch means engages the flat part of saidsecond cam track and to energize the ignition circuit, the rotor isturned to the ignition position whereby the latch means engages andrides up the ramp of said second cam track and the opposite free end ofthe rotor spring means engages the stop with further rotation of therotor in the same direction moving the rotor to the stop positionthereby twisting the rotor spring means and moving the latch means tothe end of the ramp whereupon the latch means is urged by its springmeans into engagement with the fiat part of the second cam track, andupon release of the rotor, the rotor spring rotating the rotor to itsignition position and during such return movement, the latch meansfollows the edge of the wide part of the ramp and is pushed inwardlywith respect to the rotor against the action of its spring means withthe rotor upon reaching the ignition position, the latch means clearsthe wider por- Patented July 22, 1969 tion of the cam track and beingurged outwardly by its spring means into contact with the edge of thenarrower part of the ramp so that if an attempt is made to move theswitch again to its start position, the latch means engages the shoulderof the second cam track thereby preventing such movement.

One example of the present invention is illustrated in the accompanyingdrawings wherein:

FIGURE 1 is a side view partly in elevation and partly in cross sectionof an ignition switch,

FIGURE 2 is a view taken along the line 22 of FIG- URE 1, the viewlooking in the direction of the arrows, and

FIGURE 3 is a perspective view of a cam track forming part of theswitch.

The ignition switch illustrated in the drawings of the key-operated typehaving four operative positions, an off position in which the key may beremoved from the switch, a first position, achieved by turning the keyclockwise, in which the ignition and auxiliary circuits of a roadvehicle are energized, a second position, achieved by turning the keyfurther in a clockwise direction, in which the starter motor circuit isenergized in addition to the ignition circuit, and a third position,achieved by turning the key counter clockwise from the off position, inwhich only the auxiliary circuits of the vehicle are energized.

Referring to the drawings, there is provided a cylindrical casing 11which is stepped to provide a shoulder 18 and is closed at its wider endby a contact board 14. Rotatable within a narrower cylindrical part 12of the casing 11 is the core (not shown) of a cylinder lock, with thepart 12 of the casing 11 constituting the barrel of the lock. Within awider part 15 of the casing 11 is a rotor 16 which is rotatablysupported at one end in the contact board 14 and secured at its otherend to the core of the lock for rotation therewith.

The rotor 16 is molded from a synthetic resin material and is formedwith a head 17 of substantially elliptical configuration (FIGURE 2). Thehead 17 abuts against a shoulder 18 of the casing 11, and extendingaxially from the head is a hollow substantially cylindrical shank 19,formed with a pair of diametrically opposite longitudinally extendingflats (not shown) and a longitudinally extending slot 22, with the endof the shank 19 being rotatably supported in a hole 21 formed in thecontact board 14.

Surrounding the shank 19 is an annular contact plate 23 provided withprojections 24, and the hole in the plate 23 is shaped complementarilyto the shank 19 so that the plate 23 rotates therewith.

Associated with the board 14 are four contacts 26, 27, 28, 29 each ofwhich incorporates one or more terminal blades positioned externally ofthe plate 14 for connection to external circuits, and a contact portionon the interior of the plate, with the contact portions extending intoholes in an insulaing plate 35 over which the projections 24 move.

The contact plate 23 is urged towards the contact board 14 by a spring36, one free end 36a of which is engaged in the slots 22 in the shank19, and its free end 36b extends towards the inner wall of the casing11.

The rotor 16 is provided with an axially extending bore 38 ofnon-circular cross section with which is engaged a complementarilyshaped spigot which extends from the core of the cylinder lock. Byvirtue of this engagement, the rotor 16 is rotatable with the core ofthe lock. In the head 17 is a radial bore 39 containing a ball 41 whichis urged by a spring 42 into engagement with a first arcuate cam track43.

The cam track 43 comprises three angularly spaced depressions 44, 4'5,46 which are engaged by the ball 41 in the auxiliary, off and ignitionpositions respectively of the switch. The cam track 43 further includesa radially directed ramp 47 upon whichthe ball 41 rides in the startposition of the switch.

The face of the head 17 adjacent the shoulder 18 is formed with aradially extending channel 51 which is developed diametrically oppositethe bore 42. The channel 51 commounicates at its inner end with anaxially extending stepped bore 52 of generally rectangular crosssection, with a shoulder 53 being defined between the channel 51 and thenarrower part of the bore 52. A latch member 54 comprising a strip likeportion 55 having a plate like portion 56 integral therewith anddisposed at right angles thereto is engaged with the shoulder '53. Theportion 55 extends from the channel '51 towards the casing and theportion 56 is housed in the wider part of the bore 52. A spring 57 isdisposed between one wall of the bore 52 and the portion 56 of themember 54, and serves to urge portion 55 of the member 54 towards thecasing 11.

The casing 11 is formed at a position diametrically opposite the firstcam track 43 with a second arcuate cam track 58 which comprises a flatarcuate part 59 shaped adjacent the casing 11 to form a ramp 61. Theheight of the ramp 61 increases from zero at a position diametricallyopposite to the depression 45 of the cam track 43 to a maximum at aposition diametrically opposite the extremity of the cam track 43.

The width of the ramp 61 is constant up to a point diametricallyopposite to the depression 46 in the cam track 43, where it is shaped todefine a radially extending shoulder 62. The width of the ramp thendecreases from a maximum at the shoulder 62 to zero at the highest endof the ramp. By virtue of the shape of the member 54, the portion 55thereof is urged by the spring both radially towards the casing 11 andaxially into contact with the cam track 58.

When the switch is in either its off or its auxiliary position, theportions 55 of the member 54 is engaged with the flat part 59 of the camtrack 58.

When it is required to move the switch from its oif position, anignition key is inserted into the core of the lock and is rotated. Toenergize the ignition circuit of the vehicle, the key rotated in aclockwise direction to turn the rotor 16. During the rotation of therotor from the off position to the ignition position, the portion 55 ofthe member 54 engages and rides up the ramp 61 and the end 36b of thespring 36 engages a stop 37 formed as part of the cam track 43. Furtherclockwise rotation of the rotor 16 moves it from the ignition position,and in so doing twists the spring 36 and moves the portion 55 to the endof the ramp 61. Upon reaching the end of the ramp 61, the portion 55 ofthe member 54 is urged by the spring 57 back into contact with the fiatpart 59 of the track 58. If the key is now released, the spring 36rotates rotor 16 back to its ignition position. During the returnmovements from the start position to the ignition position, the portion'55 of the member 54 follows the edge of wide part of the ramp 61shoulder 62 and prevents such movement. In order to move the-switch tothe startposition, itmust first be moved to the off position wherein theportion '55 of the member 54 can engage the lower part of the ramp 61.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. An ignition switch for use in a road vehicle of the type havingignition and starter circuits, comprising a casing, a rotor mounted forrotary movement within the casing, a first cam track formed within thecasing having depressions corresponding to auxiliary, off and ignitionpositions, a radially directed ramp adjacent the ignition positioncorresponding to the start position and a stop adjacent said auxiliaryposition, a second cam track formed within said casing, said second camtrack being provided with a flat arcuate part constituting a ramp, theheight of which increasesfrom Zero at a position diametrically oppositethe depression corresponding to the 0115 position to a maximum at aposition diametrically opposite the end of the first cam track, theWidth of the ramp being constant up to a point diametrically oppositethe depression corresponding to the ignition position, with the ramphaving a radially directed shoulder at said point and the width of theramp decreasing from a maximum at the shoulder to zero at the highestend of the ramp, spring means operably related to said rotor, saidspring means having opposite free ends with one end engaged with thevrotor and the opposite free end extending toward the inner wall of thecasing, said rotor havinga spring loaded member normally urged intoengagement with said first cam track, said rotor further having a latchmeans located substantially diametrically opposite said spring loadedmember, and spring means normallyurging the latch means towards thecasing, the arrangement being such that when the switch in either theoff or auxiliary position, the latch means engages the flat part of saidsecond cam track and to energize the ignition circuit, the rotor isturned to the ignition position whereby the latch means engages andrides up the ramp of said second cam track and the opposite free end ofsaid rotor spring means engages the stop and further rotation of therotor in the same direction moves it to the start position therebytwisting the rotor spring means and moving the latch means to the end ofthe ramp with said latch means upon reaching the end of said ramp beingurged by its spring means into contact with the flat part of said secondcam track and upon release of the rotor, the rotor spring rotates saidrotor to its ignition position during which movement said latch meansfollows the edge of the wide part of the ramp and is pushed inwardlyagainst the action of its spring means and with said rotor reaching theignition position, the latch means clears the wider portion of saidsecond cam track and is urged outwardly by its spring means into contactwith the edge of the narrower part of the ramp.

References Cited FOREIGN PATENTS 6/1962 Germany. 3/1961 France.

